This invention relates to connectors for fiber optic cables. In particular, the invention relates to an improved fiber optic connector that allows quick connection and disconnection with mating connectors, and that is resistant to signal interruption.
Fiber optic communication cables typically include at least one light transmitting optical fiber clad in an optically insulating material. The cladding prevents dispersion of light out of the optical fiber. The fiber optic cable usually has a protective external buffer over the clad fiber, typically of a plastic material, such as nylon, which may or may not be removed to terminate the cable. Optical cables usually have an outer protective layer, called a jacket, which is typically made of PVC or polyurethane material. A yarn-like sleeve, typically made of KEVLAR polymer, is often placed between the buffer and the jacket to improve the tensile strength of the cable.
The growing use of fiber optic systems creates a need for a connector capable of optically coupling a segment of fiber optic cable to another optical device, such as an amplifier, diode or other active component; a switch or other circuit; or another segment of fiber optic cable. To achieve efficient light transfer, the connector must align and space the optical elements, with or without touching whichever is specified, with high precision. The alignment and spacing requirements are exceedingly demanding, due to the minute, micron-size diameter of the optical elements (e.g., fibers) being connected, coupled or otherwise terminated. During light transmission through the coupled elements, it is essential to maintain the precision alignment and spacing (or contact) of the coupled elements, otherwise a signal interruption occurs, i.e. the optical coupling deteriorates or fails.
One method of avoiding signal interruption is to design connectors that screw together, or are otherwise permanently or semi-permanently secured together. However, there is a need for optical connectors that resist signal interruption and that also allow quick connection and disconnection with mating connectors.
One problem with known connectors of the quick connect and disconnect type is that they are prone to inadvertent signal interruption. One known optical connector which allows quick connection and disconnection, and is marketed under the ST .RTM. mark, has a captive bayonet nut for mating with a bayonet receptacle, a body for supporting the optical fiber along an axis, and a spring. The body has a front end which exposes a facet end of the optical fiber for optical coupling with another optical element. The spring serves two functions: it pushes the facet end forward, towards the optical interface to maintain optical connection, and it pushes the mating bayonet receptacle to maintain the mechanical coupling of the two bayonet members.
If the back of this prior connector body, or its attached optical cable, is pulled with a force sufficient to compress the spring, the facet end is displaced axially backwards, away from the mating optical element, and signal interruption occurs. A signal interruption can also result from lateral forces applied on the back of the connector and which displace the facet end of the connector laterally, thus causing optical disconnect through fiber misalignment.
Another problem with known quick connect and disconnect connectors is that they provide only limited protection of the coupled optical elements from corrosive agents in the operating environment. There accordingly is a need for optical quick connect and disconnect connectors that can operate in hostile environments, such as in the presence of moisture or dust.
Accordingly, an object of this invention is to provide a fiber optic connector that allows quick connection and disconnection with ST.RTM. compatible and other optical connectors, and that resists signal interruption, even when the connector or its associated optical cable is stressed, either axially or laterally.
It is also an object of the invention to provide a fiber optic connector that accommodates an environmental seal for sealing out moisture, dust, and like contaminants.
These and other objects and features of the invention will be apparent from the following description and the drawings.